There is generally known a printing apparatus which is connected to a network and prints out in accordance with a print request from a client machine. Further power saving in the printing apparatus is desired in terms of both the power cost and environment.
For a conventionally known printing apparatus, there is proposed a mechanism targeting power saving of not only a print engine but also a controller (to be referred to as a video controller or process means) for an image process or the like in order to further save power.
In this proposal, the waste of CPU power used for monitoring is considered as a problem because an external communication request is conventionally monitored by a CPU which forms a controller. To solve this problem, this proposal discloses a mechanism of monitoring whether data have been received from external host computers, i.e., monitoring external accesses from a 1284 interface, USB interface, and 100BT interface by an always ON communication I/F (communication controller) including a reception buffer and the like while powering off the controller including the CPU. This mechanism stops power to the controlling including the CPU, and allows receiving an external print request.
There is also proposed a printing apparatus which gives attention to the fact that many irrelevant data exist in a network. In this printing apparatus, the communication I/F determines whether data is related to the printing apparatus, by determining a packet addressed to the printing apparatus on the basis of an IP address contained in ARP data. When the IP address of the printing apparatus is confirmed, the controller is powered on to achieve efficient recovery by power-on.
The proposed printing apparatus performs network access on the assumption of an APR packet containing an IP address to the printing apparatus itself. The printing apparatus cannot cope with a case in which a host computer searches for a plurality of devices, degrading the function of the printing apparatus system.
Moreover, the proposed printing apparatus must energize the whole communication I/F including a detector which detects connections to a local interface (e.g., USB) and LAN (Ethernet), a reception buffer which operates the CPU of the main body controller when communication via the USB or Ethernet is detected, and various controllers. From this viewpoint, there is a room for improvement in further power saving.
As a measure, power supply to the communication I/F may be simply stopped. However, when an external host computer requests any operation of the printing apparatus, the printing apparatus does not respond to it, and the function of the printing apparatus is not fulfilled. Needless to say, when the printing apparatus does not respond to external access, the main power supply may be manually turned on with low user convenience.